Liquid level control apparatus



Aug. 25, 1953 A. s. PARKS- a 2,649,771

LIQUID LEVEL CONTROL APPARATUS Filed July 16, 1949 4' Sheets-Sheet 1 54 /z C F4 50 Asbury J. Par/ *5 D [NI/[N70]? 20b 22 MW LL-m- 5 MM 20 77 521% ATTOfP/VEVJ Aug. 25, 1953 s, PARKS v I 2649771 LIQUID LEVEL CONTROL APPARATUS .Filed July-l6, 1949 "4 s eets-she s: 2*

Asbury J. Pork;

'f/VVfNTOR MW EEJW A 7'TOR/VEK5 1953 A. s. PARKS 2,649,771

LIQUID LEVEL CONTROL APPARATUS Filed July 16, 1949 4 Sheets-Sheet 3 C 6] 620' I 22 v 65 59 I 2/ X\ Z0 6/ Asb'ury J. Pork;

[NI/[N706 awu Patented Aug. 25, 1953 UNITED STATES PATENT OFFICE LIQUID LEVEL CONTROL APPARATUS Asbury Sloan Parks, Houston, Tex.

Application July 16, 1949, Serial No. 105,203

11 Claims- (Cl. 137-413) This invention relates to new and useful improvements in liquid level control apparatus and relates particularly to controlling the liquid level Within pressure vessels, such as oil and gas separators.

The usual type of liquid level control employs a float which is located inside of the vessel and this float has connection through a shaft or operating member which extends through the wall of the vessel with mechanism located exteriorly of the vessel for operating a liquid outlet or dump valve. With such arrangement the movement of the float due to the rise and fall of the liquid level will function to open and close the outlet or dump valve and thereby maintain a predetermined level within the vessel.

As operating pressures within the vessel increase, efficient packing off around the movable shaft or operating member of the connecting mechanism presents a problem; also, the size of the float Within the vessel must be reduced to increase its strength in order to withstand the higher operating pressure without collapse. The

action of the higher pressure against the packing arrangement which seals around the movable operating member causes excessive friction against said operating member and this, coupled with the fact that the size of'the float must be reduced, greatly decreases the efliciency of the apparatus. It will be evident that the smaller float provides less power for operation while the higher operating pressure increases friction. Thus, it has been found that the simple type of apparatus wherein a movement of an internal float is transmitted through the wall of the vessel to an exteriorly located outlet or dump valve is not at all satisfactory under higher operating pressure conditions.

In an attempt to accurately control levels within pressure vessels, certain types of "torque tube apparatus have been employed. In this type of apparatus the float element is actually a solid member and said float is suspended from the outer end of a tubular torque tube, which tube has its inner end fixed and permanently sealed to the wall of the vessel. The outer end of the tube which projects into the vessel is sealed closed and a float-carrying arm is attached to said outer end, whereby the float element producesa torsional stress in the tube in accordance with the liquid level. The float element has more or less buoyancy in accordance with the liquid level and changes in this buoyancy result in a the end of the tube outwardly through the wall of the vessel, a solid operating rod is disposed axially within the tube and has its end attached firmly and sealed to the closed projecting end of the tube. The torsional movement of the torque tube, in accordance with changes in the buoyancy in the float element, is imparted to the solid rod so that the opposite end of said rod disposed exteriorly of the vessel will undergo a rotational movement. This arrangement requires that the torque tube be sufiiciently flexible to transmit the float motion to the operating rod and to make the tube sufiiciently flexible in torsion it must either be very thin walled or small in diameter or both. It is impossible to reduce the wall thick-- ness of the tube in the higher pressure vessels because of danger of collapsing or crushing of the tube, and therefore, the result has been that the torque tubes are extremely small in diameter, relatively speaking, which makes the operating rod which extends axially within the tube also very small. Actually, this rod. as commonly used is about one-eighth of an inch in diameter and is of considerable length, possibly about eighteen inches. The final result is that the float energy must be transmitted through this very small rod of considerable length which is in itself very flexible. Because of this flexibility it is impossible to apply any appreciable load to the operating end of the rod outside of the vessel and therefore, the usual type of torque tube transmitting apparatus is limited to the operation of a control mechanism that requires an absolute minimum of power.

The usual type of control employed with the present torque tube apparatus ordinarily comprises a pilot valve having a small nozzle with a flapper type valve for opening and closing said nozzle. A constant stream of pilot gas bleeds from the nozzle at all times and the movement of the flapper valve as controlled by the float position varies the back pressure on the system which feeds the nozzle, and this variation in back pressure is transmitted to a pressure-actuated liquid outlet or dump valve. A constant bleeding type of pilot is slow in operation and has the major disadvantage of requiring a constant flow of pilot gas, which constant flow causes freezing of the pilot supply regulator and in addition creates difliculty in that clogging of the very small bleed ports and openings constantly occurs. It is, therefore, apparent that the conventional torque tube apparatus is limited to controlling the operation of constant bleeding type pilot controls due primarily to the fact that suflicient energy cannot be transmitted through the apparatus to operate any mechanism which requires considerable power. Actually, the major energy or work performed by the float element is expended in twisting the torque tube or the operating rod rather than being transmitted exteriorly so that it may be utilized in operating the pilot control.

It is one object of this invention to provide an improved liquid control apparatus wherein the energy from an internal float element is efiiciently transmitted to the exterior of a pressure vessel whereby a non-bleeding type of pilot control may be actuated by the position of the liquid level with respect to the float element, therebyi'making it possible to accurately control the exterior of a pressure vessel wherein the torque tube proper is of sufiicient diameter and wall thickness to support a relatively heavy float element which will insure an ample source of energy for operating purposes and also where n said tube is slotted longitudinally to impart torsional flexibility thereto without correspondingly reducing its bending strength, whereby said energy from the float element may be transmitted through the tube without excessive energy loss.

Another object of the invention is to provide an improved liquid level control apparatus wherein the pilot pressure control unit is constructed so that the main outlet or dump valve may be actuated either with a snap or quick-opening and quick-closing action or with a throttling action, either action being accomplished without any major change in the control unit which makes the unit readily applicable to all types of pressure vessels and to all operating conditions.

Still another object is to provide in combination with an improved torque tube assembly a pilot pressure control unit which operates on a force-balance principle, whereby a constant bleed of the pilot supply is not necessary and also whereby modulation or control of the pilot pressure in accordance with changes in the liquid level being controlled may be accomplished with substantially zero motion of the operating shaft connected with the float element.

Another object is to provide an improved unit for imparting a snap or quick-opening and quickclosing action to a liquid outlet or dump valve, which unit is extremely simple in construction whereby positive operation thereof is assured.

A particular object of the invention :is to :provide an improved snap control unit comprising a double-acting valve in conjunction with a pressure-responsive member, with the effective areas of the valves and pressure-responsive .member being so related with respect to each other that the attainment of a predetermined control'lpressure will actuate the unit to place full liquid level within a pressure vessel which operates under relatively high pressure conditions.

An important object or the invention is to provide an improved liquid level control apparatus wherein the main force-transmitting or operating shaft or rod which is controlled by a float element within a pressure vessel will undergo extremely slight motion 'in controlling the operation of a liquid outlet or dump valve, whereby ordinary elastic pressure seal packing may be utilized to efiiciently seal off around the operating shaft and whereby friction ordinarily created by the higher pressure acting against the packing will not increase frictional resistance to movement of said shaft to thereby assure maximum eiiiciency of the transmission f nergy 'closing liquid outlets or "dump valves and having a simple adjusting means which allows the liquid level in the vessel, as well as the dumping range of the outlet valve, to be accurately adjusted .and controlled.

Another object of the invention is to provide an improved torque tube assembly for operating a control mechanism, which assembly is exceptionally rugged in construction and capable of withstanding high operating pressures and is also readily applicable to horizontal or vertical pressure vessels; the assembly comprising a minimum number of parts having minimum weight which facilitates mounting :of the assembly without the necessity'of the usual heavy flanges, special packing and the like.

A further object is to "provide an improved torque tube assembly for transmitting a force from the interior to the pilot pressure on the main valve to be 'operatedto actuate the valve in one direction and decrease of the control pressure will permit an exhaust of pilot pressure from the main valve; the device operating sub-- stantially instantaneously to impart a quick-closing action to themain valve.

Other and further objects of this invention will appear from the :following description.

In the accompanying -drawings which form a vpart of the instant "specification, which are to parts in :the various views:

:Figure 1 is .an elevation of a pressure vessel which is shown as 'an oi-lzandg-as separator having improved liquid level control apparatus con- .structed in accordance with the invention mountedthereon,

Figure 2 is an enlarged elevation of the 'pilot control unit and its connection with the operating rod on the exterior of the vessel,

Figure 3 is :a horizontal, cross-sectional view taken'on theline 133 of Figure 2,

Figure 4 :isatransverse verticalsectional view taken on theline 4-4 otEigure Figure 5 is :a sectional view taken on the .line 5-5 ofIFigureA,

Figure '6 :is an enlarged rdetail 10f the adjust- .ment between ithe :Qperating .rod :and the pilot unit,

Figure '7 is apartial isometric View of the inner end of the torque tube and "operating rod showing'the =connection.,of .bhGLfiQat element with said rod,

Figure 8 is a vertical sectional view :of the combined pilot control unit and the snap control unit,

Figure 9. is a view partly in section and partly in elevation of one type of outlet-on-dump valve which may be controlled by the-apparatus,

Figure 10 is a view of a modified form of the pilot :control :unit when said unit is used by it- .self without the-snap control:unit, and

Figure 11 .is a sectional view of the snap control unit whenthe same is'constructed as aseparate element, rather than :combination with .the;pilot unit asinFigurezB.

In the drawings, the numeral I designates a pressure vessel which may be an oil and gas separator and which is illustrated as having aliquid outlet pipe or line II in its lower portion. A liquid outlet or dump valve I2 is connected in the pipe II and opening and closing of this valve will control the escape or dumping of liquid from within the vessel III. The valve may be of any suitable construction and, as illustrated in Figure 9, includes a valve body I3 having a valve seat I4 therein with a valve element I5 movable with respect to the seat. When the valve element I5 is raised flow through the outlet pipe II is permitted and seating of the valve will, of course, shut 01f flow through said line.

The valve element I5 has a stem I6 which has its upper end connected with an operating diaphragm I! and said diaphragm is normally urged downwardly by a coil spring I8 to urge the valve toward a seated position. The pressure of the spring may be adjusted in the usual manner by an adjusting screw I9. When the pressure in the chamber I'Ia below the diaphragm I'I reaches a predetermined point as controlled by adjustment of the spring I8 the valve element I5 is opened to allow escape of liquid from the vessel I0 while a reduction of the pressure in the chamber I'Ia to a predetermined point will permit the spring to close said valve element. This typeof valve may be operated with a. throttling action by maintaining a predetermined pressure in the chamber IIa which will maintain the valve element I5 in a desired or predetermined position with respect to its seat in which case a controlled constant discharge of liquid from the vessel will occur. A pilot pressure fluid is conducted to the chamber I Ia below the diaphragm by a pilot pressure line which has one end connected in the diaphragm case and its opposite end connected to a suitable source of pilot pressure fluid. The particular construction of the liquid outlet or dump valve I2 is subject to some variation and so long as the valve is a motor valve or pressureactuated, either pressure-opening or pressureclosing, its operation may be controlled by the improved apparatus to be hereinafter described.

For controlling the operation of the outlet or dump valve I2 a torque tube assembly generally designated A (Figure 1) is mounted in the wall of the vessel I 0 and this assembly includes a solid float element B which is suspended within the interior of the vessel. The torque tube assembly is adapted to transmit energy or force from the float element to a pilot pressure control unit C which is located exteriorly of the vessel. A pilot pressure supply line 2| extends from a suitable source of pilot pressure into the unit C and operation of the unit 0 modulates or controls the pilot pressure to be employed in actuating the liquid dump valve I 2. If the valve I2 is to be operated with a snap or quick-opening, quick-closing action, a snap control unit D may be combined with the pilot pressure control unit C. A by-pass line 22 conducts the controlled pilot pressure from the upperportion of the unit C to a base member C and if the snap control unit is employed, this pressure is utilized to actuate said unit D. The pilot pressure line 20 may extend from the unit D to the chamber Ila beneath the diaphragm I! of the outlet or dump valve I2. If the snap control unit D is not employed and the valve I2 is to operate with a throttling action, then 'the line 20 is connected t h member C to conduct the controlled or modulated pilot pressure directly to the diaphragm I! of the valve I2.

The float element B is a solid piece of material which would ordinarily sink within the liquid being controlled but since the float element is suspended from the torque tube assembly, it is actually supported or suspended from said assembly. As the liquid within the vessel rises and falls with respect to the float element B said element becomes more or less buoyant and this degree of buoyancy of said float element is utilized to transmit energy through the torque tube assembly to the pilot control unit C to control the pilot pressure which either actuates the snap control unit D or which is applied directly to I the diaphragm I! of the outlet or dump valve I2. Thus, as the liquid level within the vessel I0 rises to a predetermined point to lighten the effective weight of the float element B the pilot unit is actuated to control the pilot pressure and effect opening of the outlet or dump valve I2 to discharge liquid from the vessel II]. As the liquid level within the vessel I0 falls due to the discharge of the liquid through the dump valve I2 the decreased buoyancy of the float element B due to the falling liquid will result in operation of the pilot control unit C to control the pilot pressure and effect closing of said dump valve and a shutting off of the discharge of liquid from the vessel. It is, of course, understood that if the snap control D is employed the valve I2 opens and closes in accordance with the liquid level; if the unit D is omitted the valve I2 will operate with a throttling action and the valve element I5 will seek an adjusted position allowing a constant controlled discharge of liquid. In either event, the control unit C controls the operation of the valve I2.

The torque tube assembly A (Figures 4 and 7) includes a torque tube 23 which may be made of considerable diameter and of relatively thick wall thickness, whereby it is sufficiently strong to support the weight of the float element B without bending. In order to impart torsional flexibility to the tube 23 said tube is split or slotted alon a longitudinal axis to form an elongate slot 24 which extends parallel to the axis of the tube. One end of the tube is welded at a single radial point 25 to a collar 26 which is formed on the inner end of a supporting flange or plate 21. The supporting flange 21 is insertable within a coupling nipple 28, which is welded at 29 to the wall I0a of the vessel I0, and said nipple has its bore aligned with an access opening 30 formed in the wall of the vessel. The flange 2'! has an annular peripheral enlargement 3| which abuts the outer end of the coupling nipple 28 and a coupling nut or union 32 is adapted to overlie .the flange 2'! and to engage threads 33 on the outer end of the nipple 28 whereby the flange having the torque tube 23 connected therewith may be mounted in the wall of the vessel I0. An O-ring 34 disposed within an annular groove 35 in the flange or plate 21 and seals off between said flange and the nipple 28. With the flange mounted in position within the coupling nipple and with the torque tube 23 extending inwardly into the vessel the weld 25 which connects the tube to the collar 26 is preferably disposed on top of said tube with the longitudinal slot 24 extending along the bottom of said tube and with such disposition of the slot, the bending strength of the tube is not materially reduced; if desired, the slot 24 may be located at any other radial point.

36a of the said sleeve section. An O-ring pac ing 3Tb seals off between the holder 31 and the bore of the sleeve section.

A cyl ndrical driveor operating bar 33 extends axially through the torque tube 23 and through the bore 35a. of the sleeve and flange and the -major portion of this drive bar has a diameter slightly less'than the diameter of the bores 23a and 36a. The inner end of the drive bar is formed with an integral enlargement or head 3? having a diameter substantially equal to the bore of the tube and the enlargement 39 is connected to the tube through a transverse pin 28 which is mounted within the enlargement 3t and which has its ends projecting into diametrically opposed openings H formedin the wall of the tube 23. As is clearly shownin'Figure 5, the diameter of the connecting pin '46 is less than the size of the openings M whereby .the connection between the operating 'or .drive bar 38 and the torque tube is somewhat of a loose connection with some play being permitted betweenthe parts.

Beyond the enlargement 39 on the drive bar 38 the bar is formed with a reduced pin &2 and the'innerend ota supporting arm' it is attached thereto. The arm is clamped against the enlargement 39 in a desired position by means of a clamping nut 44 (Figure'l). The arm i3 extends radially with respect to'the drive bar and has its outer end pivotallyconnected by a pin 45 with the upper end of an arm it to which the float element B is attached. It will thus be evident that the float element B is suspended by means of the arm 43 from the end of the drive bar 38 and the weight of this float element, because of its suspensionby means of the arm, will place the bar under a torsional stress. The bar is connected by the pin '49 and opening ii to the end of the torque tube 23 which tube'is fastened at the single radial point to the main supporting flange 27. 'The torque tube 23 actually functions to support the drive bar and in order to permit the tube to undergo torsional movement the longitudinal slot 24 "is provided in the tube. It is obvious that a relatively large diameter tube is very stiff and rigid in torsion andby providing the elongate slot 24, torsional flexibility is imparted to the tube without substantially weakening the tube so far as bending stresses are concerned. By providing a torque tube constructed in this manner a suiflciently strong tube capable of supporting a relatively heavy float element B is provided, and yet said tube is sufliciently flexible in torsion so that it does not materially interfere with the torsional stresses imposed upon the drive bar, to provide for sensitivity. It might be noted that the stress in the tube 23 under torsion is along an axial plane on the surface and the longitudinal slot 24 permits motion of the tube to occur along anaxial line with the result that torsional flexibility in the tube is produced.

The outerend of the drive bar 38 .isformed with a reduced shank 41 and beyond .the shank the bar is further reduced to provide a cylindrical 8 -extension48whichfunctions as a small bar. The shank 41 and extension 48 project through the bore 31a of the bearing holder 3'! and a seal is formed between the extension and the bor 3160 by a suitable elastic packing such as an O-ring or rubber collar 49. To reduce friction between the extension 48 and the supporting element a bearing assembly BI is mounted within the bearing holder 31 and surrounds the extension 18. It is noted that the extension as undergoes only extremely slight rotative movement in operation and the elasticity .of the packing 45 is suincient to allow the slight rotative movement of the extension therein without the necessity of a sliding contact between the surface of the extension 48 andsaid packing. This means that there is substantiall-y no frictional resistance set up :by the packing to the slight rotative movement of the extension.

In the operation of the-torque tube assembly the weight B which is a-solid mass is suspended from the supporting arm 4-3 attached to the end of the drive bar :38. The drive bar has its outer reduced extension 48 :disposed exteriorly of the vessel with this end being supported within the sleeve section :36 of the main supporting flange or plate 27, while its inner-end is supported and connected with the :torque tube 23. The weight of th float element :B will impose a torsional stress on the-drive bar 3B :and assuming that it is suspended in'atmosphere a predetermined torque will beimparted to said bar, this torsional stress also being transmitted to the torque tube 23 through the'pin wand openings '4 I.

When the assemblyis mounted within the pressure vessel and the liquid withinsaid vessel rises into contact with the float element B, the effective weight of the float element will "be reduced by the'weight'of thaliquidwhich said element displaces. As the liquid arises higher with respect to the float element 3 the effective weight of the float element .flS decreased proportionally to the liquid rise. Similarly as the liquid fall with respect to the float element the eflective weight of said element is :increased. Actually, there is no appreciable'movement of. the float element as the liquidrises and falls with respect thereto'but due to'the buoyancy 'ofthe element the effective weight beingimposed upon the drive bar and resulting a predetermined torsional stress on said bar is varied. As the effective weight of the element 3 changes to vary the torsional stress on the bar the forcezrepresented by the torsional stress is varied accordingly. This variable force :is, of course, presentinthe reduced extension 58 of the bar which is disposedexteriorly of the vessel and. said force changes without any appreciable rotationof thedrive bar because actually, said force .is represented .by .a greater or lesser torsional twisting .of the shaft 38.

It thus becomes obvious that as .theliquidlevel within the vessel varies withrespect to the float element B the force which is transmitted through the drive bar and to its extension 48 is varied in direct proportion to the changes in liquid level. This variable force which is transmitted to the reduced extension 'of "the drive bar located exteriorly of the vesselis utilized to control the pilot control unit C which in turn controls operation of the dump valve 12. If the snap control unit .D'is employed'rise of the liquid level to a prewithin the lower portion of the housing '59.

the extension 48 of the drive shaft 38 functions to again actuate the pilot control unit C and snap control unit D and thereby close the outlet valve. It is noted that if the valve I2 is actuated with a throttling action the particular torsional stress in the drive bar, as controlled by the liquid level controls the position of the valve l2 and said valve may remain partially open at all times to allow a predetermined constant escape of liquid from the vessel.

For transmitting the variable force which is representative of liquid level within the vessel from the extension 48 of the drive bar 38 said extension has one end of an operating arm 52 fastened thereto by means of a split clamp 53. A U-shaped carrier 53 is slidable to various positions on the free end of the operating arm 52 and a screw 54 is threaded through the extending ends of the carrier 53 (Figure 4). A lock nut 55 threaded on the upper portion of the screw locks said screw in adjusted positions with respect to the carrier and also functions to lock the carrier 53 in adjusted positions longitudinally of the operating arm 52. The lower end of the screw '54 is adapted to rest upon and engage a pivoted lever 56 which is mounted on a pivot pin 51, said pin being disposed below the free end of the operating arm 52. In this manner any force transmitted through the extension 48 is imparted to the arm 52 and causesna downward force to .be exerted by the screw 54 upon the lever 56.

It will be evident that by adjusting the carrier '53 and pin 54 with respect to the extension 46 of the drive bar which is the pivot point of the operating arm 52, the distance between the ex- 62a in the upper portion of the bore 62 of the casing. A valve 65 is adapted to engage the seat 64 and has a valve stem 66 having its upper end threaded into a depending shank 6'! provided in the lower portion of a tubular element 68. A diaphragm 69 spans the upper end of the bore 62 of the housing and the outer periphery thereof tension and the screw 54, as well as the distance between said screw and the pivot pin 51 of the lever 56 is varied to change the mechanical advantage from the drive bar to the lever. If the :mechanical advantage is high, a relatively small change in buoyant force on the float element B will result in considerable downward force being exerted by the lever 56; on the other hand if the :mechanical advantage is low, a greater variation :in buoyancy is necessary to produce the same applied downward force by said lever and thus by adjusting the carrier 53, it is possible to adapt the control mechanism to either throttling or snap-action operation of the liquid dump valve 12 since this adjustment determines the spread between opening and closing of the dump valve al2. Adjustment of the screw vertically to en- ;gage the lever 56 with more or less force determines the working level of the liquid, that is, the level to which the liquid will rise or fall before the valve l2 opens or closes.

The force from the drive bar extension 48 is transmitted through the operating arm 52, screw :54, and lever 56 to a force transmitting or oper- ;ating member or pin 58 of the pilot control unit C. The member 58 has a conical upper end so as to engage the lever 56 with a point contact. The pilot control unit is illustrated in Figure 8 and comprises a casing or housing 59 having an .inlet opening 66 at one side thereof. A pilot sup- -ply.line 2| is connected into the opening 66 which :communicates with a chamber 6| located axially An saxial bore 62 extends upwardly from the chamber 6| and has a valve seat collar 63 provided "with an annular valve seat 64 threaded therein. The collar 63 has an axial bore 63a extending "therethrough whereby flow. fromthe pilot supply line 2| may enter the chamber BI and then flow :upwardly past the valveseat 64 into a chamber is clamped between the u per end of the casing or housing 59 and a locking ring "it. The diaphragm 69 has a central opening through which the shank 61 of the element 68 extends and a clamping nut ll clamps the inner portion of the diaphragm to said element 68. A locking screw 12 which is threaded within the lower reduced axial bore of the element 68 engages the upper end of the valve stem 66 and permits an adjustment of the valve stem with respect to the element 68.

The force transmitting or operating member 58 of the pilot control unit is hollowed out and has its lower edge engaging the upper edge of the tubular element 68 which carries the valve 65. The interior of the member 58 and the enlarged upper portion of the bore of the element 58 form a chamber 13 which has communication with the area below the diaphragm 69 through a vertically extending passage 13. The member 58 is flanged and may undergo limited upward movement with respect to the element 68 but is confined against complete upward displacement by a retaining cap 74 which is threaded onto the upper end of the casing 59. The area of chamber 62a below the diaphragm but above the valve seat communicates through an inclined passage i5 with an opening Within which one end of the conductor 22 is threaded and said conductor has its lower end threaded into an opening it formed in a base member ll. The opening it 7 com-- municates with a chamber 18 formed axially within the base 71 and said chamber is also in communication with an opening it which may be connected with the line 26 leading to the dump valve i2 if a throttling action is desired; if the snap control unit D is employed to actuate the valve 12 with a snap action, the opening 19 will be plugged, as will be explained.

In the operation of the pilot control unit C and assuming the valve 65 to be in a closed position a pilot fluid under a predetermined constant pressure is present in the line 2| and in the chamber 6| and is acting against the under side of the valve 65 to assist in holding said valve seated. 'When a predetermined force occasioned by torsional twist in the drive shaft 38 is imparted to the operating arm 52 and is then transmitted through the screw 54 and lever 55 to the operating member 58 of the pilot unit, this force acts through the member 58 and element 68 to urge these parts downwardly and thereby move the valve 65 downwardly. As soon as the valve 65 is unseated pilot pressure is admitted into the chamber 620, below the diaphragm 69 and this pressure immediately acts upon the diaphragm to tend to move said diaphragm upwardly which is, of course, in opposition to the downwardly acting force on the operating member 58. Immediately that the admitted pressure in chamber 62a balances the force being applied to the member 56 the valve 65 is re-seated but at this time a predetermined pressure has been built up in the chamber 620. and also in the chamber 73 in the base member ll. Continued application of force to the operating member 58 through the drive shaft 38 and its associated mechanism will result in the valve 65 again opening but immediately upon opening sufiicient pressure acts against the under side of the diaphragm 69 to immediately balance the applied force but this results in a further increase in pilot pressure chambers 62a and 78. It thus becomes apparent that with the particular pilot control unit the application of a force to the operating member 58 to unseat the valve 65 immediately admits pressure which balances the applied force to reseat the valve and thus a gradual building up of pressure Within the chambers 62a, and It occurs. This increase is directly proportional to the force applied to the operating member 58 and as ex-- plained, the applied force is actually representative of liquid level in the vessel Hi. The controlled or modulated pilot pressure within the chambers 52a, and I8 is also present in the chamber 13 formed between the valve supporting element 68 and the operating member 53 but at this time the applied force acting downwardly on the member is sufficient to hold these parts in en gagement with each other.

The continued application of force to the operating member 58 of the control unit C finally results in building up the pressure in the chambers 62a and it to the predetermined point necessary to effect operation of said valve to either open said valve l2 or if the valve is already open to open it further and thereby allow a discharge of liquid from the vessel ill. Fall of the liquid level within the vessel results in a decrease in the force applied to the member 58, and decrease of this applied force to a point which permits the pressure present within the chamber it formed between the operating member 58 and the valve supporting element 68 to overcome said force causes separation of the member 58 from the element 53, whereby pressure from the chambers 52a and i8 is vented to atmosphere through the axial opening 14a. in the retaining cap 75?. Escape of pressure from the chambers 52a and '58 reduces the pressure on the main outlet valve to allow said valve to close or move toward a closed position. The variation in pilot pressure in the chambers 62a, and i8 is directly proportional to the applied force and the force applied is con trolled by the liquid ievel in the vessel; therefore, variations in the modulated or controlled pilot pressure are in accordance with changes in the liquid level.

If the liquid dump valve 62 is to be operated with a throttling action the line 2i! is connected in the opening 19 the base so that the pressure in the chamber 13 is conducted directly to the diaphragm chamber Ha (Figure 9) of the valve 12. This pressure is modulated or controlled directly in accordance with the applied force which is representative of the liquid level and with such a direct connection between the chamber 62 a and the motor valve l2, said motor valve will be throttled or automatically adjusted to permit a constant controlled discharge of liquid from the vessel i l! to maintain a desired level within the vessel.

It is pointed out that because the pilot unit C functions to immediately balance the force which is applied to the member 58, substantially zero motion is necessary in the drive bar 38, the operating arm 52 and lever 56 because as soon as movement of these parts begins the valve 65 within the unit C opens and is then immediately closed by the balancing pressure. This slight motion is an important feature of the invention since it permits efficient packing on" around the drive bar extension 46 due to the fact that there is substantially no rotative movement of the extension within the packing 49. Actually, the slight rotative movement of the extension is a rocking or oscillating motion of the extension within the packing with the elasticity of the packing permitting such motion while the packing remains in tight frictional engagement with the extension. Thus there is no sliding contact between the surface of the extension and the packing and frictional resistance to the motion of the extension is minimized, which makes the apparatus operable under exceptionally high pressures without danger of leakage.

As pointed out the line 28 (Figure 8) is connected to opening 19 leading from the chamber '58 when a throttling action is desired. It is many times desirable that the valve l2 be actuated with a snap action, that is, quick-opening and quick-closing, and in such event the snap control unit D is employed. In Figure 8 this unit is illustrated as combined and incorporated with the pilot control unit C while in Figure 11 it is illustrated as a separate unitary device. Referring to Figure 8, the snap control unit D com prises a generally cylindrical housing 89 which is mounted between the casing 59 of the unit C and the base T1. The housing has an axial bore which is enlarged at its lower end to form a chamber 8512. A valve assembly is mounted Within the housing and includes an upper valve disc 8! having an annular valve seating ring 82 and a lower valve disc 84 having an annular valve seating ring 35, the discs being connected by a shank 83 which extends through the bore Bila. The upper valve 82 is disposed within the cham-. ber ti in the lower portion of the unit C and has its valve ring 82' adapted to engage a flexible seat 38 provided on the upper end of the housing. The lower valve has its valve ring 85 adapted to engage a flexible valve seat Ell pro vided at the intersection of the bore 8% and the chamber 8th.

The diameter or area of the valve 82 at its seating position is of a greater cross-sectional area than the diameter of the valve 85 at its point of seating and the length of the connecting shank 83 is such that when one of the valves is seated, the other is unseated. The lower end of the chamber SE31) is closed by a flexible diaphragm 38 which spans the lower end of the housing 89 and which has its peripheral edge portion clamped between the housing and the base H. The lower'valve disc St is adapted to be engaged by the upper surface of the diaphragm 88 and the effective cross-sectional area of said diaphragm is greater than the effective seating area of the upper valve 2. The diaphragm actually functions as the top of the chamber it in the base 11 and is therefore exposed to the pressure within said chamber. A restricted port or vent 89 to atmosphere is formed radially within the housing -86 and communicates with the chamber 8% below-the lower valve seat S l. A threaded outlet opening 1% extends radially through the housing and is located between the upper and lower valve seats 86 and It! and has one end of the line 20 connected therein; the other end of said line is connected to the diaphragm chamber 11a of the outlet :or dump valve I2.

Vl/nen the snap control unit Dis employed a plug 2% shown in dotted lines in Figure 8 is threaded into the opening "it which extends from the chamber in the base 11 and the line 2%; connects the opening ill] of the snap control 13 unit with the diaphragm chamber Ila of the outlet or dump valve. In the operation of the snap control unit the constant supply pilot pressure from the line 2| is present within the chamber 6! and is acting on the effective cross-sectional area of the upper valve 82 to hold this valve downwardly in a seated position. As the applied force on the pilot control unit operating member 58 is increased to increase or build up the pressure within the chamber 62a. and also within the chamber 18 within the base 11, this increased pressure acts against the diaphragm 88 and tends to urge the valve discs 84 and 8! upwardly. The relationship between the area oi the diaphragm 88 to the area of the valve 82 will control the point at which the modulated or controlled pilot pressure in chamber 78 will move the valve 82 upwardly off of its seat. When this point is reached and the pressure in chamber 18 is sufficient to move the valve 82 upwardly,

- the valve 32 is unseated to admit the full pilot pressure to the bore 934a of the housing 88 and to the line 28 which leads to the liquid outlet valve diaphragm ll'. At the instant that the pressure in the chamber 18 acting against the diaphragm 88 overcomes the constant supply pressure acting to hold valve 82 seated, both the lower valve 85 and upper valve 82 are snapped upwardly and the action is so rapid due to the sudden release of force holding the valve assembly down that the lower valve 85 moves into engagement with its seat 81 before the pilot pressure can fill the volume of the bore 88a between the upper and lower valves 82 and 85. As noted the area of the valve 85 is less than the area of the valve 82 and thus, the pilot supply pressure which is tending to move the valve downwardly off of its seat is acting on the lesser area of the valve 85. Because the effective area of the diaphragm 88 is considerably larger than the area of the lower valve 85, the valve 85 will be held seated against the full pilot pressure and said pilot pressure is conducted to the diaphragm of the liquid outlet or dump valve 52 to open the same with a snap or quick opening action.

Opening of the valve l2 allows the discharge of liquid from the pressure vessel [8 and results in a reduction of applied force to the pilot operating member 58 and .as this force reduces sufliciently to allow the pressure in the chamber 13 formed between the operating member 58 and element 88 to overcome this applied force the pin 58 is separated from the valve carrying element 88 to allow a venting of pressure'irom chamber 78 to atmosphere to effect a reduction in pressure in said chamber 18.

Obviously, the pressure will continue to redues in the chamber 18 until the full pilot pressure acting on the lower valve 85 is sufiicient to unseat this valve and move the assembly downwardly. As the valve 85 begins to leave its seat there is a momentary leakage of I pilot gas under this seat outwardly through the vent openin 89 and since the diameter of this opening is relatively small a back pressure is built up within the chamber 8% above the diaphragm 88. This back pressure immediately acts on the top side of the diaphragm 88 and causes saiddiaphragm to move downwardly to remove all resistance to lowering of the valve disc assembly and the pilot pressure in chamber 6i again seats the upper valve 82. The pressure which was acting upon the dump valve 12 through the line 20 then bleeds outwardly to atmosphere through the, exhaust or vent opening .89 and thevalve [2 .moves to :14 a closed position. Theparts remain in this position until the applied force again builds up the vmodulated or controlled pressure within the chamber 18 at which tim t e p r ti n s peated. V

The arrangement which combines the units C and D, as illustrated inFigure 8, is adaptable for use in controlling the liquid outlet or dump valv 12 either witha throttling action or with a snap or quick-openingand quick-closing action. As has been noted, if a snap action is desired the opening 19 in the base 11 is plugged by the plug 281) and flow to the outlet or dump valve is through the line 28. If a throttling action is desired the plug 28b closesthe port 96 and the line 28 connects with the outlet valve.

In the event that the outlet or dump valve is to be actuated solely with a throttling action th pilot control unit C may be constructed as a separate unit which is illustrated in Figure 10. The construction would be the same as shown in Figure 8 except that the chamber Gla in the lower portion of the casing 59 will be omitted and a completely closed chamber 61' substituted therefor. In this event the line 22 of Figure 8 is eliminated as is the base l1 and the conductor 28 leading to the outlet or dump valve i2 is connected directly into the opening 15a extending from the inclined passage '15 which communicates with the chamber 62a below the pilot operating diaphragm 69.

The snap control unit D may also be constructed as a separateunit and in Figure 11 such an arrangement is illustrated. In this instance, the snap control unitD includes a casing as having a chamber 63' at its upper end and a chamber 18' at its lower end, these chambers being closed by closure plates 9| and 92, respectively. A line 22' extends from a pilot control unit to control the pressure in the lower chamber 18' while the conductors 28 and 2| are connected to the casing 88 in the same manner as hereinbefore described. It is evident that the operation of this unit will be, identical to the operation as described with respect to the unit shown in Figure 8.

The apparatus provides a very sensitive and accurate control Iorcontrolling the liquid level in a pressure vessel. The improved torque tube assembly A comprises a minimum number of parts which are of minimum weight and may be readily connected with any pressure vessel either of the horizontal or vertical type. The provision of the pilot control unit C makes it possible to control or modulate'the pilot pressure without any substantial movement of the drive rod 38 since actually the rod 38 is merely a force transmitting element. This assures efficient packing on" under exceptionally high pressures around the rod which is the only member extending through the wall of the pressure vessel sincesaid rod-does not have a sliding rotative contact with the packing 49 and frictional resistance is thereby minimized. The particular mechanism which transmits the applied force from the drive rod to the control unit C permits an adjustment whereby the level to which the liquid will rise within the vessel, and the operating range between opening and closing of the dump valve [2, may be accurately controlled.

In the operation of the apparatus the float element or weight B is suspended within the vessel on th end of the drive rod 38 which is connected to the end of the torque tube 23. The torque tube is-anchored or fixed by theweld 25 to the supporting flange and thus, the weight of the float element sets up or creates a predetermined twist or torquein the drive rod. This torque, under atmospheric conditions, will apply a predetermined force to the pilot operating member 58 of the pilot control unit C. The float element or weight is illustrated as suspended from that side of the rod 38 which will cause the rod to apply force in a clock-wise direction in Figure 6 as the liquid level rises around the float element. As said liquid level rises around the float element the effective weight of the float element is reduced by the weight of the displaced liquid and this reduction in the efiective weight of the float will result in a decrease in the torque or twist in the drive rod extension 18 which will tend to move the operating arms 52 downwardly. Actually, there is no appreciable movement in the arm but rather the reduction in torsional twist in the drive rod extension 48 will produce a downward force on the screw 54 which is transmitted through the pivoted lever 56 to the forcetransmitting or operating member 58 of the control unit 0.

Continued rise in liquid level within the vessel around the float element 3 results in further reduction in eliective weight of said element and .a resultant increase in applied forc to the operating member 58 of the pilot control unit C whereby the controlled or modulated pressure .in chamber 62c builds up to a predetermined point. When the pressure the chamber 62a and the chamber is in communication there- Operation of the liquid dumpvalve 12 results in a fall of the liquid level around the heat element Band this increases the effective Weight of said float element with the result that an increased torsional twist .is imparted to the drive rod 38. ,sional twist in the rod lessens the force which is applied through the operating arm 52 and lever 56 to the operating member 58 of the pilot control unit and when this force decreases to a predetermined point as controlled by the adjustment of the screw 54 and the adjustment :of the carriage $3 the pressure within the chamher 13 of the pilot unit separates the member 58 from the valve carrying element '68 and allows escape of the pressure from the chamber '78. It is noted that the element -63 and its co- ;action with the operating member "SS-oi the pilot control unit form a relief valve which permits venting of pressure to atmosphere. decrease in the force being applied tothe operating member 58 to a predetermined point, the :snap control unit D shuts oil pressure to the outlet valve 1 2 or if the snapper is notemployed Increased tor- Thus, upon reduction in the pressure throttles the outlet valve to an adjusted position.

Any rise or fall-o'f th'e liquidleVel in the vessel will immediately vary theefiective weight-of the float element and this increase or decrease in effective weight of the float element 5 is instantaneously converted in'to-a torsionaltwist in-the drive rod 3 8 whichis instantaneously"transmitted to the pilot-control unit C as an applied force. As has been -notedlthe "pilot control unit includes means for immediately balancing the applied force with the result that subs'ta'ntially Zero motion of the shaft 38, o'perating arm 52, lever 56 and ope'rating pin sais had. The apparatus is extremely sensitive to very small changes iri liquid level because the slightest change in liquid level will vary the applied force on the control unit. Accurate adjustment of the controlled or modulated pressure in accordance with liquid level changes may be accomplished by means of the force transmitting mechanism which consists of the operating arm 52 and lever 56. together with its associated carriage 53 and adjusting screw 55.

It will be evident that the particular pilot control unit is so arranged that the constant pilot supply pressure is present in the conductor 2i and this pressure is permitted to enter the chamber 62a in accordance with the applied force. As the applied force increases the pressure in chamber 82 increases and it is this controlled or modulated pressure which is utilized to operate the dump valve I2 either by a throttling action directly through line 2c or by a snap action through the snap control unit D. The snap control unit is arranged so that when the modulated or controlled pilot pressure reaches a predetermined pressure which is representative of liquid level the snap control unit operates to place the full pilot pressure from conductor 2! on the operating diaphragm of the dump valve 12; similarly, when a pressure drop in the modulated or controlled pressure occurs to a predetermined point the snap control unit I) functions to immediately shut off communication between the pilot supply conductor 2! and the operating diaphragm of the valve l2 and at the same time to permit bleeding of the line 25! which extends from said dump valve. The pilot pressure system is such that a constant bleed of the pilot pressure is not required but rather a closed system is en'lployed. The only time that pilot pressure disohargedto atmosphere is when it is desirable to reduce the pressure to either throttle the valve it toward a closed position or to fully close said valve when the snap control unit D is employed. There are no small orifices or nozales which might cause freezing due to pressure drop thereacross or which might become clogged and thisis one of the features of the invention since it eliminates difficulty which is occasioned with the present type of constant bleed type pilot controls.

The torque tube assembly A is exceptionally rugged in construction with the tube being of considerable :size and of sufficient strength to support a relatively heavy float-element B. fhe longitudinal slot 26 which is formed in the torque tube is preferably located at the lowerendof said tube so as to provide .xnaximum resistance to bending of the tube while forming a minimum resistance to torsional twist said tube. With this arrangement the energy which is transmitted to the drive rod 38 by the weight is :utilized to its fullest extent by converting substantially all of said energy into applied .force at the pilot control unit. There is a minimum energy loss due to frictionalresistance in the system between the suspended arm 33 which carlies the weightand the point of application of force to the operating member I58 of the pilot unit C. Such minimum-energy loss provides for extreme sensitivity in the control whereby liquid levels -may be'accurately controlled to a desired degree. Althcughthe supporting arm :43 is illustrated as substantially straight, said arm may be curved to facilitate insertion of the torque tube assembly and'theattached weight into the access opening 30 in the wallof the vessel. It

. is also pointed out that the liquid outlet dump valve [2 has been illustrated as a pressure-opening valve but said valve may be pressure-closing, in which event the decrease in modulated or con trolled pilot pressure would effect opening of said valve.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure.

It will be understood that certain features and subcombinations are of utility and may be employed Without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having described the invention, I claim:

1. A control assembly responsive to variations in liquid level within a vessel including, a selfsupporting torque tube having one end secured to the inner wall of a pressure vessel and projecting inwardly intothe interior of said vessel, said tube having a longitudinal slot extending from end to end thereof, which slot functions to weaken Q the tube in torsion, a drive bar extending axially through the torque tube and connected to said tube at the free end of the tube, said bar also projecting through the wall of the vessel to the exterior thereof, means for sealing on" around the drive bar to prevent escape of pressure from the interior of the vessel, and a float element suspended from the inner end of the drive bar.

2. A control assembly responsive to variations in liquid level within avessel including, asupport having an axial bore therethrough adapted to be removably mounted and sealed within an access opening in the wall of a pressure vessel, a self-supporting torque tube having one end secured to the inner surface of the sup-port and projecting into-.the interior of the vessel, said tube having a longitudinal slot extending from end to end thereof, which slot functions to weaken the tube'in torsion,a drive bar extending axially through the'support and torque tube with its outer end located exteriorly of the vessel and its inner end within the vessel beyond the torque tube, means for connecting the inner end portion of the bar to said tube, sealing means surrounding the bar and engaging the bore of the support for sealing off around said bar, a radially extending supporting arm attached to the extreme inner end of the bar, a float element secured to the arm, and a force-transmitting member mounted on the extreme outer end ofthe drive bar.

3. A control assembly responsive to variation in liquid level within a vessel including, a support removably mounted and sealed within an access opening in the wall of a pressure vessel, a relatively elongate generally tubular member having one end secured to the inner surface of the support and projecting inwardly into the interior of said vessel, said member having a longitudinal slot extendingfrom end to end thereof with the longitudinal edges which define said slot being spaced from each other, said slot imparting a low resistance to torsional deflection of the member without weakening its resistance to bending, a drive bar extending longitudinally of the elongate member and connected to the member at a point spaced from the point of attach- 18 ment of the member to the support, said drive bar projecting outwardly through the support with its outer end located exteriorly of the vessel, sealing means between the bar and the support for sealing off around said bar, and a fluid displacement member suspended from the inner end of the drive bar.

, 4. A control assembly responsive to variations in liquid level within a vessel including, a supporting member having one end secured to the inner wall of a pressure vessel and projecting inwardly into the interior of said vessel, said member having high resistance to bending and having a structural shape which provides a pair of longitudinal edges on the member which are unconnected and spaced from each other whereby said edges may move longitudinally with relation to each other without overlapping upon the application of torsional stress to the member to thereby impart torsional flexibility to said member, a drive element extending longitudinally of the member and having its outer end projecting through the wall of the vessel to the exterior thereof, means for sealing off between the drive element and the wall of the vessel, connecting means between the drive element and the supporting member connecting said element to said member at a point spaced from the point of attachment of the supporting member ot the wall of the vessel, said connecting means permitting limited longitudinal movement of the member with respectsto the drive element while maintaining a rotatable connection between said member and element, and a fluid displacement member suspended from the inner end of the drive bar.

5. A control assembly responsive to liquid level within a vessel including, a support removably mounted and sealed within an access opening in the wall of a pressure vessel, a member which is relatively elongate with respect to its width, said member having one end adjacent to the inner surface of the support and its opposite end projecting inwardl into the interior of said vessel,

edges on the member which are unconnected and spaced from each other, whereby said edges may move longitudinally with relation to each other without overlapping upon the application of torsional stress to the member to thereby iinpart torsional flexibility to said member, a drive bar extending longitudinally of the member and connected to the member at a point spaced longitudinally from the point of attachment of the member to the support, said drive bar projecting outwardly through the support with its outer end located exteriorly of the vessel, sealing means between the bar and the support for sealing off around said bar, and a fluid displacement member suspended from the inner end of the drive bar.

6. A control assembly responsive to variations in liquid level within a vessel including, a support adapted to be removably mounted Within an access opening within the wall of a pressure vessel, sealing means for sealing between said support and the vessel, a torque tube having one end secured to one end of the support and projecting into the interior of the vessel, said tube having a longitudinal slot extending from end to end thereof, said slot having a width which spaces the longitudinal edges defining said slot from each other, whereby said edges may undergo movement relative to each other in a longitudinal direction without overlapping when a torsional stress is applied to the tube, said support having an axial bore which is aligned with the bore of the torque tube when the tube is secured thereto, a drive bar extending axially through the bore of the support and the bore of the tube with its outer end located exteriorly of the vessel and its inner end within the vessel beyond the torque tube, means for sealing 011 between the drive bar and the support, means for connecting the drive bar to the tube at a point spaced from the point of attachment of the tube to the support, a float element suspended from the inner end of the drive bar, and a force-transmitting member mounted on the outer end of the drive bar exteriorl of the vessel.

7. A control assembly as set forth in claim 6, wherein the connection between the drive bar and the torque tube is relatively loose to permit limited longitudinal movement of the torque tube with respect to the drive bar while maintaining a rotatable connection between the member and bar.

8. A control assembly as set forth in claim 5, wherein the removable mounting of the support includes a housing surrounding the access opening in the vessel wall for receiving the support and also wherein the support is retained within the housing by a retaining collar having threaded connection with the housing, loosening of said collar Without detachment thereof from the housing maintaining the seal between the support and vessel while permitting rotational movement of the support with respect to the housing to efiect an adjustment of the position of the fluid displacement member within the vessel.

9. The combination with a pilot pressure control unit having an actuator for operating the control unit by the application of a variable force and having a means therein for balancing the applied force, of a control assembly responsive to variations in the liquid level within a vessel which assembly comprises, a drive bar extending through the wall of the vessel, a supporting member for the drive bar having high resistance to bending and having a structural shape which provides a pair of longitudinal edges on the member which are unconnected and spaced from each other, whereby said edges may move longitudinally with relation to each other without overlapping upon the application of torsional stress to the member to thereby impart torsional flexibility to said member, the member having one end attached to the inner wall of the vessel with its opposite end projecting into the interior of said vessel, means for connecting the drive bar to the supporting member at a point spaced from the point of attachment of the member to the vessel wall, a float element suspended from the inner end of the drive bar and functioning to impart torque to the bar in accordance with changes in liquid level within the vessel, and means mounted on the outer end of the drive bar exteriorly of the vessel and having a direct engagement with the actuator of the pilot pressure control unit whereb said unit is actuated in direct proportion to the variations in torque in the drive bar as controlled by variations in liquid level within the vessel.

10. The combination as set forth in claim 9 wherein the supporting member is a torque tube having a longitudinal slot extending from end to end thereof to impart torsional flexibility thereto.

11. The combination as set forth in claim 9, together with means for adjusting the force applying means which is carried by the outer end of the drive bar and which engages the actuator of the pilot control unit, whereby the operation of the control unit may be varied.

'ASBURY SLOAN PARKS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,992,212 Horne Feb. 26, 1935 2,123,652 Klein July 12, 1938 2,248,322 Annin July 8, 1941 2,263,771 Grifiey Nov. 25, 1941 2,269,846 Engel Jan, 13, 1942 2,416,570 Coleman Feb. 25, 1947 2,459,527 Herbert Jan. 18, 1949 2,476,030 Evering July 12, 1949 FOREIGN PATENTS Number Country Date 806,889 France Oct. 5, 1936 872,258 France 1942 

